The invention relates to the field of active optical elements, in particular to carry out an ophthalmic lens. In particular, the invention relates to the field of ophthalmic lenses which are adapted to correct two different visions, for example near vision and far vision. It is the case for presbyopic wearers who need a first ophthalmic correction for near vision and a second ophthalmic correction for far vision which is different from the first ophthalmic correction.
It is a common practice in the art to use multifocal lenses for improving comfort to presbyopic wearers. Nevertheless, traditional multifocal lenses, such as bifocal and trifocals, suffer from a number of disadvantages. There is a desire to improve the performance and cosmetic appeal of multifocal lenses. As an example, many traditional multifocal lenses have a visible discontinuity separating each vision zone. Blended multifocals can reduce the visibility associated with these abrupt discontinuities but generally at the cost of rendering the blend zones optically unusable due to high levels of distortion and/or astigmatism. Traditional progressive lenses can provide multiple vision zones with invisible boundaries and no image breaks but these lenses typically have narrow vision zones and are associated with large amounts of unwanted astigmatism.
U.S. Pat. No. 7,976,158 B2 describes another type of ophthalmic lenses which procure, for a wearer, corrections adapted for his foveal vision and for his peripheral vision. The eyeglass has a central zone that produces a first correction and a peripheral zone. The peripheral zone is divided into first and second contiguous regions. The first and second regions alternate and are dedicated to obtaining two respective ophthalmic corrections for the wearer of the finished eyeglass produced from the lens. Thus, the first and second regions are dedicated to obtaining respectively a first and a second correction, the second correction differing from the first correction. Furthermore, the first correction provided by the first regions is identical to that produced in the central zone. According to the invention, the first ophthalmic correction is determined for correcting the foveal vision of the wearer of the finished eyeglass and the second ophthalmic correction is determined for correcting the peripheral vision of this wearer. These two ophthalmic corrections differ from each other.
However, it may be difficult for a wearer to get used to this type of lenses that integrate two different ophthalmic corrections.
Other known solutions in the art introduce active optical system in order to solve these problems.
U.S. Pat. No. 7,883,207 describes multifocal lenses having one or more multifocal inserts comprising one or more diffractive regions. A diffractive region of a multifocal insert provide a constant optical power or a progression of optical power, or any combination thereof. A diffractive region of a multifocal insert is positioned to be in optical communication with one or more optical regions of a host lens to provide a combined desired optical power in one or more vision zones.
U.S. Pat. No. 5,815,233 A describes a liquid crystal active lens having, in combination, a fixed-focal-point lens having a high index of refraction and a phase modulation element comprising two-dimensionally arranged fine pixels, and having power and being capable of electrically controlling the lens characteristics as a function of space. An electrically controlled optical system is realized without having a moving portion. Owing to the combination of the liquid crystal element for modulating space phase and the high-power lens of a fixed focal length, it is possible to electronically control the focal length and to electronically control the lens in a spatially split manner.
These active optical systems are very complex and difficult to implement.
In consequence, there is a need, and particularly for presbyopic wearers, for a simple active system of vision integrating two different ophthalmic corrections which does not present problems of wearer adaptation and with no image breaks as in bifocals and trifocals lenses.
So, the invention is directed to an active system of vision integrating two different ophthalmic corrections and improving comfort to a wearer. The method carried out by the active system of vision and the active system of vision itself are simple to implement.